In the skeletally mature individual, hyaline articular cartilage does not heal effectively when injured and the natural progression of acquired articular cartilage defects is predictably poor, commonly culminating in joint arthrosis. Physician and patient demands are fueling interest in biological resurfacing and restoration as an alternative to prosthetic joint replacement in an active patient population with an increased life expectancy. Fresh osteochondral allografting currently remains the only treatment option that reliably restores anatomically appropriate, mature hyaline cartilage in weight bearing osteoarticular defects. This transplantation paradigm is associated with unique challenges mostly related to balancing the essential and seemingly conflicting considerations of graft safety with timely patient-donor matching. Maximizing the storage interval of allograft tissue has become a focal topic in tissue banking by extending cold storage times and optimizing storage media. Our recent studies determined that (1) serum-enhanced 4[unreadable]C storage media is superior to both modified serum-free storage media and lactated ringer's solution for allograft storage, (2) chondrocyte viability of allografts declines rapidly after 14 days of 4[unreadable]C storage in culture media, with (3) the superficial zone of the cartilage appearing preferentially affected, (4) and that these changes are induced in part by upregulation of apoptotic and matrix-related gene expression, and (5) that 37[unreadable]C storage media maintains chondrocyte viability for up to 4 weeks. Also (6) impact insertion of osteochondral grafts induces chondrocyte death with a similar pattern of the superficial zone being preferentially affected. While results using traditional fresh allograft protocols have been consistently good even in long-term follow-up, the clinical consequences of prolonged cold storage of articular cartilage on chondrocyte health and overall graft quality remain largely unquantified. Likewise, while mechanisms of cartilage injury sustained during graft insertion have been postulated, their extent and clinical effect on graft performance have not been established in vivo. The objectives of this proposal are to investigate how storage parameters and insertion modality affect chondrocyte viability, and, consequently, the efficacy of osteochondral allografts in vivo by (1) testing innovative modifications to allograft storage method in vitro, and (2) to determine effects of storage and select allograft insertion techniques on graft performance and clinically relevant outcomes in vivo. PUBLIC HEALTH RELEVANCE: The proposed research will foster understanding of the performance of osteochondral allograft transplants in the treatment of cartilage injury and disease. This may lead to improved clinical outcomes in affected individuals, as well as decreased disability associated with joint injuries and subsequent arthritis.